Physical environmental attributes and helmet use in an Indian metropolis: An ecological study

Background: Road traffic injuries (RTIs) and fatalities among powered two-wheeler (PTW) users are associated with helmet use. Though individual-level reasons for not wearing helmets are well researched, evidence regarding macro-level environmental reasons is limited from an Indian context. Objective: To test for the association between physical environmental factors (temperature, windspeed, pressure, humidity and visibility) and helmet use in Bengaluru city. Methods: Session and location-wise observational data of helmets were collected by NIMHANS and Johns Hopkins' International Injury Research Unit (JH-IIRU) across 15 randomly selected locations in Bengaluru city in 2021. This was merged with physical environmental data (temperature, wind speed, humidity, pressure, visibility and rainfall) extracted from www.timeanddate.com, specific to location and time of helmet data collection. Univariate and correlation analyses were performed to test for the association between physical environmental attributes and helmet use rates. Results: A significantly negative correlation was found between pressure and helmet use, while a significantly positive correlation was found between humidity and helmet use. No significant correlation was found between wind speed, temperature, visibility and helmet use rates. Conclusion: Contrary to popular belief, we did not find any significant association between temperature and helmet use rates. However, helmet use positively correlated with humidity. Ecological fallacy is expected in the interpretation of the results.